.main{
    display: flex;
    flex-direction: column;
    align-content: space-between;
    justify-content: space-between;

    flex-grow: 0;
    flex-shrink: 0;
    min-height: 100vh;
    background-color: cornflowerblue;
}

header {
    display: flex;
    flex-direction: row;
    justify-content: space-between;
    align-items: center;
    flex-grow: 0;
    flex-shrink: 0;
    min-height: 10vh;
    background-color: aquamarine;
}

.home_page:nth-child(1) {
    border: none;
    background-color: rgb(158, 209, 211);
    border-radius: 5px;
    min-width: 10vw;
    text-align: center;
    line-height: 40px;
    height: 40px;
    margin-left: 1vw;
    margin-right: 4vw;
}

.home_page:nth-child(1):hover {
    color:ivory ;
    background-color:rgb(64, 142, 145);
}

header> a {
    border: none;
    background-color: none;
    color: darkslategrey;
    min-width: 5vw;
    margin: 1vw;
}

header> a:hover {
    border: none;
    background-color: none;
    color: deeppink;
}

#search {
    display: flex;
    flex-direction: row;
    border:none ;
    min-width: 5vw;
    margin-right: 3vw;
}

.dropdown {
    display: inline-block;
    border: none;
    background-color: none;
    color: darkslategrey;
    min-width: 5vw;
    margin-left: 3vw;
}

.dropdown_content {
    display: none;
    position: absolute;
    background-color: rgba(167, 133, 221, 0.822);
    color: beige;
}

.dropdown:hover .dropdown_content {
    display: block;
}

.group {
    display: flex;
    flex-direction: row;
    align-items: center;
    min-width: 20vw;
}

.search[type="text"] {
    height: 3vh;
    width: 15vw;
}

.search[type="text"]+button {
    border: none;
    background-color: rgb(158, 209, 211);
    color: rgb(12, 20, 22);
    width: 5vw;
    height: 3.6vh;
}

.search[type="text"]+button:hover {
    background-color: rgb(64, 142, 145);
    color: ivory;
}

footer {
    flex-grow: 0;
    flex-shrink: 0;
    min-height: 10vh;
    background-color: burlywood;
}

footer {
    text-align: center;
    line-height: 10vh;
    font-size: 3vh;
    color: gray;
}

.following {
    display: flex;
    flex-direction: row;
    justify-content: space-between;
}

#left_aside {
    /* flex属性依次包括flex_grow flex-shrink flex-basis */
    flex: auto auto 1 ;
    width: 20vw;
    background-color:rgb(255, 196, 0);
    color: ivory;
}

.l_button {
    display: flex;
    flex-direction: column;
    align-items: center;
    position:fixed ;
    top: 21vh;
    left: 11vw;
}

.l_button> button {
    border: none ;
    background-color: deepskyblue;
    border-radius: 30px;
    width: 35px;
    height: 35px;
    margin: 10px;
}

.l_button>button:hover {
    background-color: rgb(227, 236, 240);
}

.l_button> div {
    border: none;
    opacity: 0;
    margin-bottom: 20px;
    margin-top: 5px;
}

.center {
    flex:auto auto 2 ;
    width: 40vw;
    background-color:  rgba(167, 133, 221, 0.822);
    padding: 3vh;
}

.center>.text {
    margin-left: 1vw;
    margin-right: 1vw;
    margin-bottom: 3vh;
    margin-top: 3vh;
}

.center>.img:nth-child(1) {
    display: flex;
    flex-direction:row;
    justify-content: space-around;
    border: none;
    background-color: none;
    margin: 3vh;
}

#screen_shot {
    width:37vw ;
    align-content: center;
}

.right {
    display: flex;
    flex-direction: row;
    flex:auto auto 2 ;
    width: 40vw;
    background-color:palevioletred;
}

#right_aside {
    flex:auto auto 1 ;
    width: 20vw;
    background-color:olivedrab;
}

.user {
    display: flex;
    flex-direction: column;
    flex: 0 0 auto;
    min-width: 17vw;
    justify-content: center;
    align-items: center;
    margin: 2vh;

    border: none;
    background-color: rgb(167, 211, 66);
}

.user_inf {
    display: flex;
    flex-direction: row;
    align-content: center;
    align-items: center;
    justify-content: start;
    width: 15vw ;
}

#u_img {
    border: 5px solid olivedrab;
    width: 6vw;
    height: 9vh;
    margin-right: 1.5vw;
}

#u_img img {
    width: 100%;
    height: 100%;
}

#u_space {
    border: none;
    border-radius: 5px;
    background-color:khaki;
    text-align: center;
    height: 3vh;
    width: 7vw;
}

#u_space a {
    color: rgb(145, 59, 153);
}

#u_space a:hover {
    color: olivedrab;
}

.link {
    display: flex;
    flex-direction: column;
    flex: 0 0 auto;
    justify-content: space-between;
    align-content: center;
    margin: 1vh;
}

.link>a {
    border: none;
    background-color: rgb(95, 159, 202);
    color: lightgoldenrodyellow;
    font-size: 4vh;
    text-align: center;
    min-width: 17vw;
    margin:1.4vh ;
}

.link>a:hover {
    background-color: rgb(142, 185, 214);
    color: rgba(24, 24, 26, 0.253);
}

.content {
    display: flex;
    flex-direction: column;
    align-content: center;
    position: sticky;
    top: 0;
    color: ivory;
    margin: 3vh;
}

.content>h2 {
    margin-bottom: 0vw;
}

.content_link>div {
    border: none;
    background-color:rgb(167, 211, 66);
    min-height: 4vh;
    margin: 2vh;
    text-align:center;
    line-height: 4vh;
}

.content_link>div:hover {

    background-color: olivedrab;
}

.content_link>div>a {
    font: 300;
    color: rgb(32, 32, 14);
}

.content_link>div>a:hover {
    color: ivory;
}
